1. Field of the Invention
The present invention relates to a display device and a method of fabricating a display device, and more particularly, to a liquid crystal display device and a method of fabricating a liquid crystal display device.
2. Description of the Related Art
In general, cathode ray tube (CRT) devices have been commonly used to display images. However, due to their size and weight limitations, the CRT devices are increasingly being replaced with liquid crystal display (LCD) devices that are small sized and lightweight, and have low profiles and low power consumption.
The LCD devices include an array substrate upon which thin film transistors (TFTs) are arranged, a color filter substrate upon which red, green, and blue color filter layers are formed and which is attached to the array substrate, and liquid crystal material interposed between the array and color filter substrates. The array and color filter substrates are formed by patterning and etching metal and insulating layers using photolithographic processes including several masking steps.
Fabrication of the array substrate includes a first mask step, wherein a metal layer is deposited onto a transparent glass substrate and then etched to form a gate bus line and a gate electrode. Next, during a second mask step, a gate insulating layer, an amorphous silicon film, and a doped amorphous silicon film are coated on the transparent glass substrate to form an active layer. Then, a third mask step includes depositing a source/drain metal film onto the glass substrate and patterning the metal film to form source/drain electrodes on the active layer and a data bus line. During a fourth mask step, a passivation film is deposited onto the glass substrate and a contact hole is formed in the passivation film. Then, during a fifth mask step, an ITO transparent film is deposited onto the substrate and etched to form a pixel electrode.
Fabrication of the color filter substrate includes depositing a chrome or resin-based material onto a transparent insulating substrate, and patterning it to form a black matrix having a lattice structure. Then, red (R), green (G), and blue (B) color resins are coated on the transparent insulating substrate upon which the black matrix is formed, wherein the coated R, G, and B color resins are exposed to light and developed to form a color filter layer within pixel regions defined by the black matrix. The black matrix is formed to have the lattice structure corresponding to the gate bus lines and the data bus lines along a periphery of the active regions of the TFT array substrate, thereby preventing light leakage along a periphery of the array substrate.
FIG. 1 is a plan view of a liquid crystal display device according to the related art. In FIG. 1, gate bus lines 1a and 1b and data bus lines 3a and 3b are orthogonally arranged on a transparent lower substrate to define a plurality of unit pixel regions. In addition, thin film transistors (TFTs), which function as switching elements, are formed at crossing regions of the gate bus lines 1a and 1b and the data bus lines 3a and 3b, and pixel electrodes 9a and 9b formed of indium-thin-oxide (ITO) are disposed within the unit pixel regions. An active layer 7 is formed on gate electrodes 5 of the TFTs and includes source electrodes 6a and drain electrodes 6b, thereby forming the TFTs.
In order to protect elements on the TFT array substrate, a passivation layer 15 (in FIG. 2) is deposited on the transparent lower substrate to cover the data bus lines 3a and the source and drain electrodes 6a and 6b. Accordingly, in order to electrically interconnect the pixel electrodes 9a and 9b and the drain electrodes 6b, contact holes are formed in the passivation layer 15.
The data bus lines 3a and 3b are disposed in parallel with the pixel electrodes 9a and 9b and transmit image data to the pixel electrodes 9a and 9b. In addition, the black matrix 17 is formed on the color filter substrate and corresponds to the gate bus lines 1a and 1b, the TFTs, and the data bus lines 3a and 3b, which are all formed on the TFT array substrate, thereby preventing light leakage from a backlight device.
FIG. 2 is a cross sectional view along I-I′ of FIG. 1 according to the related art. In FIG. 2, a gate insulating layer 11, upon which the data bus line 3a is formed, is formed on a transparent lower substrate 10a. In order to protect the data bus line 3a, the passivation layer 15 is deposited on the gate insulating layer 11 to cover the data bus line 3a. In addition, an indium tin oxide (ITO) metal is deposited on the passivation layer 15 and etched to form the pixel electrode 9a. 
The data bus line 3a and the black matrix 17 overlap the periphery of the pixel electrode 9a and are formed on a transparent upper substrate 10b that faces the lower substrate 10a. The black matrix 17 is provided to intercept light incident from the backlight device except for light incident from the backlight device that passes through a liquid crystal layer (not shown) controlled by the pixel electrode 9a. 
However, in the above LCD device, light that passes through the transparent lower substrate at a certain angle is refracted by the gate insulating layer 11 and the passivation layer 15, and then passes through the transparent upper substrate 10b around the black matrix, thereby causing light leakage. For example, when light radiated from the backlight device is transmitted along a direction perpendicular to the transparent lower substrate 10a, light that passes between the data bus lines 3a is intercepted by the black matrix 17. However, any light incident at a certain angle (arrow) is refracted to pass around the black matrix-17. In order to solve this problem, a width of the black matrix 17 may be enlarged to prevent the light leakage. However, if the width of the black matrix 17 is enlarged, the aperture ratio of the pixel electrode 9a is reduced and deteriorates the displayed image quality.